Troubleshooting for Serial Interface Communications

Problem

Recommendation

Printer prints one

The LQ uses the DTR signal and the

character then stops

X-on/X-off protocol (via TXD) to tell the

 

computer whether it is ready to receive

 

characters or whether it is busy printing.

 

Refer to your computer’s documentation

 

and ensure that the computer is using

 

one of these systems. You may also need

 

to check your cable wiring or ask your

 

dealer to do it for you.

 

 

READY light flickers

Data is getting through to the printer but

but nothing is printed

is not being interpreted correctly Make

 

sure that both the printer and computer

 

are using the same baud rate, number of

 

start and stop bits, and the same panty

 

 

All printing is garbled

Make sure that both the computer and

 

printer are set to use the same number of

 

data bits per word (8) and that they both

 

use the same parity, baud rates. and

 

number of start and stop bits.

 

 

Hex Dump Mode

The LQ has a special feature that makes it easy for experienced printer users to find the causes of problems. The hexadecimal (hex) or data dump mode gives a printout of exactly what codes reach the printer.

Enter this mode by turning on the printer while holding down the

FORM FEED and LINE FEED buttons at the same time. Then, when you run a program, either an application program or one you have written in any programming language, the LQ prints, in the hex format, all the codes being sent to the printer.

The data dump below was made while writing this appendix. By comparing the guide section on the right with the printout of hex codes,

Problem Solving and Maintenance

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